Low shear mattress topper constructions

ABSTRACT

Low shear mattress topper constructions have multiple internal topper layers with at least one intermediate layer made of a low shear material and disposed between foam or other layers to reduce frictional shear forces and enable a greater degree of lateral displacement between the topper layers.

RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No. 61/485,342, filed May 12, 2011.

FIELD OF THE INVENTION

The present disclosure and related inventions is in the general field of cushion devices and products, including bedding and mattresses and sleep sets.

BACKGROUND OF THE INVENTION

In conventional mattress construction, there is a core which consists of springs, foam or other reflexive devices or materials and in various combinations. On a support side of the core there are additional components or layers of materials, referred to as comfort layers, which together with the core define the underlying support characteristics of the mattress. The core, comfort layers and other internal components of the mattress are covered by upholstery which includes one or more vertically oriented side panels referred to as the border, and a top panel over the support or sleep surface. The top panel typically includes upholstery fabric with some additional backing such as a thin layer of foam on the underside or flame resistant material, and a liner such as a non-woven sheet material. The top panel is commonly stitched throughout the entire surface area by a multi-needle sewing machine which forms a quilt-like pattern and appearance on the surface of the top panel upholstery by the compression of the fabric against the backing material. For this reason the top panel is often referred to as a “quilt panel” or “quilted topper”.

In some quilt panel constructions, additional foam layers or foam layers of greater thickness are used in an effort to improve the cushion characteristics of the uppermost region of the mattress. However, frictional shear forces between the layers of material of the quilt package can result in unevenness in the quilt upholstery surface, binding inside of the quilt package, and lateral transfer of forces through the quilt package. Also, the manufacturing of the quilt package can be problematic when there is frictional binding between the internal layers

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation cross-sectional view of a mattress including a low shear mattress topper of the present disclosure and related inventions;

FIG. 2 is a cross-sectional view of one embodiment of a low shear mattress topper of the present disclosure and related inventions, and

FIG. 3 is a cross-sectional view of an alternate embodiment of a low shear mattress topper of the present disclosure and related inventions.

DETAILED DESCRIPTION OF PREFERRED AND ALTERNATE EMBODIMENTS

The present disclosure and related inventions is directed to a cushioning and support device or assembly such as a mattress, having various combinations of materials and layers of material which provide additional cushioning and support, including multiple layers foam and a low friction or low shear layer between the layers foam which allows ease of relative movement between the foam layers for an improved feel and support performance of the comfort layers of the mattress. The low friction or low shear layer between the layers of foam creates a relatively low coefficient of friction and reduced shear forces as compared to a foam-to-foam contact interface, and allows two or more layers of foam to easily slide or deform laterally relative to each other. This also allows the uppermost layer of foam to compress and slide in a low shear or no-shear environment relative to an underlying layer of foam, without the substantial friction with the surface of the underlying layer of foam which would otherwise be encountered. The upper layer of foam is thus able to compress and move independently, and laterally in particular, relative to the underlying or adjacent layer or layers of foam, so that two or more layers of foam such as are provided in a mattress do not behave as a monolithic block of foam and do not bind or resist movement or conformance due to frictional shear forces. The combination of foam and fiber layers creates a perceptible differentiated feel on the surface of the mattress from prior art quilt constructions, and allows the foam layers to move more freely against each other by preventing the two foam layers from binding at the interface by the high friction shear forces of foam-on-foam.

As shown in FIGS. 1, 2 and 3, a representative mattress construction of the disclosure, indicated generally at 10, includes a core, generally indicated at 50. The core 50 may be of any construction, such as an array of interconnected steel wire coiled springs (innerspring) as shown in FIG. 2, wire coil springs contained in fabric material (pocketed coils) also shown in FIG. 2, one or more pieces of foam (foam core) as shown in FIG. 3, or any combinations thereof and any other support or reflexive structures or components. The representative mattress constructions 10 are illustrated as “one-sided” type mattresses, with only one side of the core designed for use as a sleep surface, and the opposite underside 55 as a mounting surface on which the mattress is supported by a foundation, frame, floor or other support structure. The low shear mattress topper constructions of the present disclosure however can be incorporated into the construction of a two sided mattress in which both sides of the core are configured for use as a sleep surface. As illustrated, the underside 55 of the core 50 can be optionally configured with one or more layers of generally planar material, indicated at 60, to provide a planar surface for mounting of the mattress on a support structure.

On the sleep surface side or sides of the core 50 are provided one or more comfort layers, generally indicated at 70, which are most commonly layers of foam, with a first comfort layer 71 placed directly over the support surface area of the core 50, and additional comfort layers such as layer 72 placed in contact with the surface area of layer 71, etcetera. Layers of materials other than foam may also be similarly incorporated into the comfort layers 70 of the mattress construction.

The mattress core 50 and comfort layers 70 are covered by upholstery, indicated at 80, which extends around the vertical sides of the mattress in the form of a border generally indicated at 81, and also a sheet material covering over the under underside 55. Upholstery 80 also extends over the topper 100, which may or may not be the same type or style material of the upholstery of the border 81. The topper upholstery 102 is attached to the border upholstery 81 along a seam, generally indicated at 90, the construction of which may further include a tape edge 92 which encapsulates the adjoining edges of the upholstery material. This is referred to as the “tape edge” or “tape edge seam” and is the primary or sole attachment of the topper 100 to the remainder of the mattress.

The topper 100 includes, in addition to the topper upholstery 102, one or more layers of topper material or mattress topper layers or mattress topper internal layers which may include foam, fibers, cotton, wool, feathers or any other synthetic or natural materials in a generally co-planar arrangement as shown. Immediately adjacent to the topper upholstery 102 is a first layer of topper material 104. Topper material 104 is preferably a fiber based material which can be adhered to substantially the entirety of the underside of topper upholstery 102 or otherwise arranged to provide support and loft to the topper upholstery 102, and which also preferably includes, is made of or treated with a flame resistant or fire retardant material as known in the art. Topper layer 104 thus serves as a flame resistant barrier which will withstand the standardized flame burn test for mattresses over the entire surface area of the topper 100. The fire resistant material for topper layer 104 may include flame and heat resistant materials such as fiber mats, woven or nonwoven fabrics, knitted fabrics, films, laminates, and flexible composites or combinations thereof. Fibers of topper layer 104 can be formed into a batt or fabric web and stitchbonded using the appropriate yarn to form a fire resistant layer. Flame and heat-resistant fibers known in the art include boron, basalt, carbon, glass, ceramic, graphite, aramid polymers, polytetrafluoroethylene (PTFE), polyimide, phenolformaldehyde, polybis-imidazole, polyvinylidene chloride, polysulfide, melamine, silicon carbide, and blends thereof.

Topper material 106 is in this embodiment a layer of foam material or the like which also extends over substantially the entirety of the topper 100 and comfort layers 70, and which is adjacent to or immediately adjacent to topper layer 104. Another topper layer 110 is also preferably made of foam, and can be of the same or different thickness than topper layer 106. Topper layer 110 as illustrated serves as a base layer of the topper 100 for primary contact with the top surface of the comfort layers 70. Between topper layers 106 and 110 is a low shear layer 108 which is preferably in the form of a polymeric fiber layer in the form of a planar mat, either spunbound or meltbound wherein the fibers are interconnected but provide loft and spacing between opposing sides of the layer, and a high degree of motion by flexure of the fibers under shear or compression. The opposing sides of topper layer 108 are preferably in direct contact with the facing surfaces of topper layers 106 and 110 and, due to the dissimilarity of materials there is a relatively high coefficient of friction at those layer interfaces, greater than the internal shear force of topper layer 108, so that topper layer 108 allows a greater degree of lateral displacement between topper layers 106 and 110 than a foam-to-foam interface. Topper layer 108 is also referred to herein as “low shear layer” and “low shear low shear insert layer”. Although described in connection with a preferred embodiment as a mat layer of fibers, any suitable material which has an internal shear force measurement, internal friction or resistance to lateral deformation which is less than the adjacent layers of the topper 100 can serve as the low shear layer in accordance with the principles of the present invention.

Stitches 112 may extend through the various layers of the mattress topper 100, for example in a quilt-like pattern in order to maintain general alignment of the layers. However, the relatively high degree of freedom of movement of topper layer 108 combined with the ability of the stitches 112 to deform with lateral forces enables the low shear motion, function and feel of the mattress topper 108.

The low shear insert layer between any two layers of foam can be any material which has a lower internal coefficient of friction than foam. This is also referred to herein as “low shear” and “low shear resistance”. Shear force as defined and used herein is an amount of force applied parallel to opposing planar surface of a layer of material of a mattress, such as a topper layer, sufficient to displace one surface of the layer or portion thereof relative to the other surface. Shear resistance as used herein refers to the tendency of a material layer of a mattress topper to resist lateral displacement of one or both major planar sides of the layer. Where the shear force of one of the layers of the mattress top of the present disclosure, such as a fiber layer, is less than the shear force of another layer of the mattress topper such as a foam layer, or less than the shear force between contacting layers of the mattress topper, it is referred to herein as “low shear” or “reduced shear” or lower “shear resistance”. One exemplary embodiment is non-woven synthetic fibers such as polyester or polypropylene which are loosely arranged in a mat form without any binding agent, so that the fibers of the mat are free for relative movement including lateral displacement. The fibers of such a mat are held in contact with the opposing surfaces of the two foam layers by compression, but are free to translate in response to shear forces exerted on the foam layers, thus allowing the foam layers to move independently. Other embodiments of low shear insert layers of the disclosure include woven sheet material, preferably of synthetic fibers which have a relatively low sliding coefficient of friction with itself and with other material such as foam. In such embodiments, even single plies of such woven material, for example one against each piece of foam at the opposing surfaces, provides a low friction foam-to-foam interface which achieves the desired performance characteristics of the disclosure. Other woven or non-woven materials include silk, polyester, polypropylene, acrylic, acetate, acrylonitrile or Rayon.

In an alternate representative embodiment the tension relief quilt or low shear mattress topper 100 includes a first layer of foam 110, the first layer of foam having a generally planar top surface and a generally planar bottom surface parallel to and opposite the generally planar top surface, and four generally planar side walls that are perpendicular to and extend between the generally planar top and bottom surfaces. The first layer of foam is positioned closest to the mattress core 50, such as an innerspring or foam core. The generally planar top surface of the first foam layer is in direct contact with a bottom surface of a first fiber layer (also referred to herein as an “low shear insert layer”). The top surface of the first fiber layer, which is opposite the bottom surface, is in direct contact with a bottom surface of a second foam layer. The second foam layer has a generally planar top surface and a generally planar bottom surface parallel to and opposite the generally planar top surface, and four generally planar side walls which are perpendicular to and extend between the generally planar top and bottom surfaces.

The first fiber layer 108, which is placed between the first and second foam layers, can be made of non-fire retardant, non-woven, non-densified, high-loft fiber. The term “non-woven” is used in the textile industry to denote fabrics which are neither woven nor knitted. Non-woven fibers are engineered fibers that are typically manufactured by putting small fibers together in the form of a sheet or web, and then bonding them together by chemical, mechanical, heat or solvent treatment. The term “non-densified” refers to fibers which have not bonded to each other through the melting and re-solidification of bonding fibers. “High-loft” is a term given to a fiber structure that contains more air than fiber. In general, high-loft fibers retain more warmth. Foam-on-foam contact creates a significant amount of friction between two foam surfaces. As a load is applied to the mattress, the two foam layers move against one another in a shearing fashion, which over time, can wear away the surfaces of the foam which are in direct contact. The first fiber layer operates to create a low coefficient of friction between the first and second foam layers. Therefore, the fiber layer must be made of material which has a slick or slippery surface. Such materials include, but are not limited to: polyester, polypropylene, nylon silk, acrylic, acetate and rayon. Eliminating friction between the first and second foam layers allows both foam layers to move independently against one another, creating a more comfortable, responsive mattress surface and also extending the life of the mattress. In a preferred embodiment, the first fiber layer, which is sandwiched between the first and second foam layers, is made of 0.5 oz. 100% polyester fiber.

The first foam layer, which is positioned closest to the mattress core or innerspring, or below the first fiber layer, can be made of any suitable foam material. The thickness, density and indentation force deflection (IFD) may vary according to the desired mattress qualities. In a preferred embodiment, the first foam layer is made of Hypersoft Quilt Polyurethane Foam having a thickness of approximately 1-inch, a density of approximately 1.15 lb/ft³ and an IFD of 14.5 lbs. Hypersoft is a super soft supple foam having an improved tear strength and permeability.

A second foam layer 106, which is positioned closest to the mattress surface, or above the first fiber layer, can be made of any suitable foam material. The thickness, density and IFD may vary according to the desired mattress qualities. In one embodiment, the second foam layer is identical to the first foam layer or a 1-inch layer of Hypersoft Quilt Polyurethane Foam having a density of approximately 1.15 lb/ft³ and an IFD of 14.5 lbs. In another embodiment, the second foam layer may be a 1-inch polyurethane layer having a density of approximately 0.75 lb/ft³. Alternatively the second foam layer may be a 1-inch polyurethane layer having a density of approximately 1.15 lb/ft³. The lower density layer positioned closest to the mattress surface results in a softer initial feel to a user sitting or lying thereon.

Optionally, a second fiber layer 104 may be positioned above the second foam layer and below the mattress tick. In a preferred embodiment, the second fiber layer is made of 0.8 oz. Light Fire Retardant (FR) or Rayon. Fire retardant material in a non-woven or low shear insert layer may increase the internal coefficient of friction of a such a layer, but the described action of the adjacent foam layers may still be achieved. Other additives which enhance the low-friction/low-shear properties could be used with non-woven layers or inserts made of other materials as disclosed. Also, any combination of materials may be used for the low shear insert layers, such a first low shear insert layer of a first type of material adjacent to a surface of a first layer of foam, and a second low shear insert layer of a second type of material which has a relatively low coefficient of friction with the first type of material positioned adjacent to an opposing surface of a second layer of foam. Other embodiments include multiple (i.e., more than two) layers of foam, with an low shear insert layer between each layer of foam, or with low shear insert layers of varying coefficients of static or sliding friction between the foam layers. Fire retardant material can be incorporated into any of the described layers of the mattress topper. 

1. A low shear mattress topper package comprising: a first foam layer having a generally planar top surface, a generally planar bottom surface parallel to and opposite the generally planar top surface and four side walls perpendicular to and extending between the generally planar top and bottom surfaces; a fiber layer having a top surface and a bottom surface parallel to and opposite the top surface, the bottom surface of the fiber layer in direct contact with the top surface of the first foam layer; a second foam layer having a generally planar top surface, a generally planar bottom surface parallel to and opposite the generally planar top surface and four side walls perpendicular to and extending between the generally planar top and bottom surfaces, the bottom surface of the second foam layer in direct contact with the top surface of the fiber layer, wherein the fiber layer is made of polyester, polyethylene, nylon silk, acrylic, acetate, rayon or a combination thereof.
 2. The low shear mattress topper package of claim 1, wherein the first and second foam layers are made of Hypersoft Quilt Polyurethane Foam.
 3. The low shear mattress topper package of claim 1, wherein the first and second foam layers are approximately 1-inch thick.
 4. The low shear mattress topper package of claim 1, wherein the fiber layer is made of 100% polyester fiber.
 5. The low shear mattress topper package of claim I further comprising a second fiber layer having a top surface and a bottom surface parallel to and opposite the top surface, the bottom surface of the fiber layer in direct contact with the top surface of the second foam layer.
 6. A mattress topper comprising an upholstery layer which overlies at least two internal layers, a first internal layer made of foam, and a second internal layer in contact with the first internal foam layer, the second internal layer comprising at least some fibers, the second internal layer having a shear resistance which is less than a shear resistance of the first internal foam layer.
 7. The mattress topper of claim 6 wherein the upholstery and internal layers are stitched together.
 8. The mattress topper of claim 6 comprising at least one additional internal layer.
 9. The mattress topper of claim 6 wherein the second internal layer is comprised substantially of synthetic fibers.
 10. The mattress topper of claim 8 wherein a shear force between the second internal layer and the first internal layer is less than a shear force between the first internal layer and the at least one additional layer.
 11. The mattress topper of claim 6 further comprising a fire resistant material.
 12. The mattress topper of claim 6 wherein the second internal layer is located between internal layers made of foam.
 13. The mattress topper of claim 6 wherein the second internal layer has an uncompressed cross-sectional thickness dimension which is less than an uncompressed cross-sectional thickness of the first internal layer.
 14. The mattress topper of claim 6 wherein the upholstery and internal layers of the mattress topper are substantially connected together at a seam located along a border of a mattress. 